Serfas
Thunderbolt Headlight

Details

Serfas' Thunderbolt Headlight delivers 90 lumens in an extremely versatile, USB-rechargeable package. Attach the water-resistant silicone body nearly anywhere on your bike, and use the high, low, or two flash modes to make sure cars, cyclists and pedestrians can see you at night. At just 50 grams, you won't even notice it's on your bike — but others will!

After seeing another rider with the tail light version of this - and seeing him almost 2km away in bright daylight - I bought the headlight version as well. There are two flash modes - you cycle through daylight full, nighttime full and then daylight flasher and nighttime flasher. This light projects both far and wide so other road users can see you. This isn't a light for you to see by, but you can see this flash over 2km away. I use it for commuting and road riding every ride and have had less run-ins with cars pulling in front of me compared to my previous light. I'll pick up the tail light next.
Easy to install and remove. I find in night flasher mode, the battery lasts a lot longer - about 8 hours. That's the mode I usually run it in, unless it's really bright out or traffic is heavy. 2.5 hours in daylight flasher mode may not be enough run time.

I purchased a front Thunderbolt and two rear bolts and have been using the product for about a year.
I don't know Mike but completely agree that it's very perplexing that cyclists aren't using lights like this in our local hills under all riding conditions.
I typically do a 40-60 mile loop ride each weekend and use the light on a constant beam 'low power' setting. It's plenty visible and in warmer weather lasts a little over four hours (colder weather usually results in shorter run time).
Unlike Mike I don't like flashing mode because descending a road like highway nine I noticed that the beam pulsing off the various signs marking the road really breaks up my concentration (I realized then how focused I am when riding at 40 mph!).
Anyway, the other day I was climbing up nine and passing in front of vehicles lined up at the temporary stop light above Redwood Gulch. I overhead one motorcyclist say to another "look, that guy has a LED strapped to his front [head] tube" and the other replying "Yeah, that's a really great idea."
Seriously, what more needs to be said? There's a reason why motorcycles use lights. It's wasn't something readily and easily available to bicyclists until recent years, but now that it is there is NO EXCUSE for not taking precautions to protect yourself. I simply shake my head when I see bikes descending King's in front of the Tripp road turnoff and realizing how easy it would be for a car to make a left in front of them and how much difference a daylight running light could make.
The light is lightweight, easy to install with a couple rubber straps, recharges quickly and is overall a great product. I never ride without them.

First things first. I own a bike shop, so sure, I make money selling these things. But I ride 7200 miles/year on the road, and this is the very best front light I've found for daytime use. Yes, daytime. Didn't used to think it was a big deal, but there have been too many accidents lately during the day, when cyclists were simply missed or blended into the background. People seeing this light often do a double-take, which is awesome. Highly recommended. --Mike Jacoubowsky, Partner, Chain Reaction Bicycles